The quality of a photograph or film often depends on accurate settings for a camera's exposure-related parameters, such as aperture settings and/or exposure times. Any settings related to exposure parameters for photographs or films will hereinafter be referred to as exposure settings. Also, the terms “photograph”, “photographer”, “photography”, and the like will be used generically hereinafter to refer to concepts related to photography and/or cinematography.
To determine the appropriate exposure settings for a photograph, the lighting conditions under which the photograph is taken might need to be determined. A photographer might use one of two different types of light meters, a reflected light meter or an incident light meter, to measure the light level. A reflected light meter is typically built in to a camera and can measure the amount of light reflected from a subject and arriving at the camera. An incident light meter is typically a stand-alone device that can measure the amount of light falling on a subject.
In most cases, a measurement by a reflected light meter is adequate for determining the appropriate exposure settings. However, when a scene is particularly bright or particularly dark, the use of a reflected light meter can result in a photograph that is underexposed or overexposed. An incident light meter might provide better results under exceptionally bright or dark conditions. A photographer can place an incident light meter near the subject to be photographed to measure the amount of light actually incident on the subject. This light measurement might then be used to determine exposure settings that are more appropriate than those that would be obtained through the use of a reflected light meter.
It can be seen that reflected light meters and incident light meters each have advantages and disadvantages. A reflected light meter can be built in to a camera, thus freeing the photographer from the need to carry an additional piece of equipment. A camera with a built-in reflected light meter can use the light level measurements made by the reflected light meter to make an automated determination of the appropriate exposure settings. However, the light level measurements made by a reflected light meter might not always lead to the most appropriate exposure settings under all circumstances.
An incident light meter, on the other hand, can take light level measurements that result in exposure settings that are correct under a broader range of lighting conditions. However, a photographer using an incident light meter typically needs to carry an additional piece of equipment and may need to manually determine the exposure settings based on the measurements made by the incident light meter.
Digital cameras are sometimes included in multi-function devices such as telephones, smart phones, personal digital assistants, handheld, tablet, or laptop computers, and similar portable devices that have wireless telecommunications capabilities. Any such device will hereinafter be referred to as a mobile telecommunications device or simply as a mobile device.